Secure distribution of video on-demand

ABSTRACT

In accordance with a first aspect, a remote server receives video programming in a first encrypted form and stores the video programming. After the remote server receives a request from a subscriber station for transmission of the video programming, the remote server decrypts the video programming, re-encrypts the video programming into a second encrypted form, and then transmits the video programming to the subscriber station. In accordance with a second aspect, a remote server receives video programming in a first encrypted form, decrypts the video programming, re-encrypts the video programming into a second encrypted form, and then stores the video programming. After the remote server receives a request from a subscriber station, the remote server simply transmits the video programming. In accordance with a third aspect, a remote server receives video programming in a first encrypted form and stores the video programming. After the remote server receives a request from a subscriber station, the remote server passes through the video content by transmitting the video programming. In accordance with a fourth aspect, a remote server receives pre-encrypted video programming and stores it. After the remote server receives a request from a subscriber station, the remote server completes encryption of the video programming and then transmits the video programming.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the field of video distributionnetworks. In particular, this invention relates to secure videodistribution networks.

2. Description of the Background Art

Security is an important issue for video distribution networks. Forcable distribution networks, there are various portions or locationswhere security is of concern.

A first portion where security is of concern is the primary distributionnetwork. The primary distribution network is where video content istransferred from television studios to distribution centers. A secondportion where security is of concern is the secondary distributionnetwork. The secondary distribution network is where the video contentis transmitted from a distribution center to subscriber stations.

For video on-demand distribution networks, there is an additional pointwhere security is of concern. That point is a remote server within adistribution center. Typically, such a remote server stores the videocontent before the video content is distributed to the subscriberstations.

SUMMARY OF THE INVENTION

The present invention provides a solution to the security issuespresented above, especially with regards to security at a remote server.In accordance with a first aspect of the invention, a remote serverreceives video programming in a first encrypted form and stores thevideo programming in the first encrypted form. After the remote serverreceives a request from a subscriber station for transmission of thevideo programming, the remote server decrypts the video programming,re-encrypts the video programming into a second encrypted form, and thentransmits the video programming in the second encrypted form to thesubscriber station.

In accordance with a second aspect of the invention, a remote serverreceives video programming in a first encrypted form, decrypts the videoprogramming, re-encrypts the video programming into a second encryptedform, and then stores the video programming in the second encryptedform. After the remote server receives a request from a subscriberstation for transmission of the video programming, the remote serversimply transmits the video programming in the second encrypted form tothe subscriber station.

In accordance with a third aspect of the invention, a remote serverreceives video programming in a first encrypted form and stores thevideo programming in the first encrypted form. After the remote serverreceives a request from a subscriber station for transmission of thevideo programming, the remote server passes through the video content bytransmitting the video programming in the first encrypted form to thesubscriber station.

In accordance with a fourth aspect of the invention, a remote serverreceives pre-encrypted video programming and stores the pre-encryptedvideo programming. After the remote server receives a request from asubscriber station for transmission of the video programming, the remoteserver completes encryption of the video programming and then transmitsthe video programming to the subscriber station. At the subscriberstation, the video programming is fully decrypted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a conventional cable distributionnetwork.

FIG. 2 is a flow chart depicting a conventional insecure process fordistributing video content via a conventional cable distributionnetwork.

FIG. 3 is a flow chart depicting a conventional (somewhat) secureprocess for distributing video content via a conventional cabledistribution network.

FIG. 4 is a schematic diagram of a cable distribution network includinga video on-demand source in accordance with a preferred embodiment ofthe present invention.

FIG. 5A is a flow chart depicting a secure process for distributingvideo on-demand content via a cable distribution network in accordancewith a first aspect of the present invention.

FIG. 5B is a flow chart depicting a secure process for distributingvideo on-demand content via a cable distribution network in accordancewith a second aspect of the present invention.

FIG. 6 is a flow chart depicting a secure process for distributing videoon-demand content via a cable distribution network in accordance with athird aspect of the present invention.

FIG. 7 is a flow chart depicting a secure process for distributing videoon-demand content via a cable distribution network in accordance with afourth aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a schematic diagram of a conventional cable distributionnetwork. The conventional cable distribution network typically includesone or more broadcast sources 102, one or more premium broadcast sources104, one or more distribution centers 106, one or more secondarydistribution networks 108, and a plurality of subscriber stations 110.

The broadcast source 102 may be, for example, a local televisionstation. For instance, an affiliate station of a major network such asABC, NBC, CBS, FOX, or UPN. The premium broadcast source 104 may be, forexample, a premium channel such as HBO, Showtime, Cinemax, and so on.The sources 102 and 104 may be coupled via a primary distributionnetwork to the distribution center 106. The distribution center 106 maybe, for example, a cable head-end. The distribution center 106 may becoupled via a secondary distribution network 108 to the subscriberstations 110. The secondary distribution network 108 comprises mayinclude, for example, various amplifiers, bridges, taps, and dropcables. Finally, the subscriber stations 110 may be, for example,set-top boxes and associated television equipment for viewing the videocontent by end users.

FIG. 2 is a flow chart depicting a conventional insecure process fordistributing video content via a conventional cable distributionnetwork. First, a non-premium video signal is transported 202 from thebroadcast source 102 to the distribution center 106. At the distributioncenter 106, the video signal is multiplexed 204 with other signals togenerate a multiplexed signal. The multiplexed signal is thendistributed 206 from the distribution center 106 via the secondarydistribution network 108 to the subscriber stations 110. At thesubscriber stations 110, the multiplexed signal is demultiplexed 208 toisolate the video signal, and then the video signal is displayed 210,typically, on a television monitor.

FIG. 3 is a flow chart depicting a conventional (somewhat) secureprocess for distributing video content via a conventional cabledistribution network. First, a premium video signal is encrypted 302 togenerate an encrypted signal. The encrypted signal is transported 304from the premium broadcast source 104 to the distribution center 106.

At the distribution center 106, the video signal is decrypted 306 toregenerate the premium video signal. The premium video signal is thenscrambled 308 and multiplexed 310 with other signals to generate amultiplexed signal. The multiplexed signal is then distributed 312 fromthe distribution center 106 via the secondary distribution network 108to the subscriber stations 110.

At the subscriber stations 110, the multiplexed signal is demultiplexed314 to isolate the scrambled video signal, the scrambled video signal isunscrambled 316, and then the video signal is displayed 318, typically,on a television monitor connected to a set-top box. The process in FIG.3 is a typical conventional process for delivering premium video usingscrambling. Other conventional processes also exist.

FIG. 4 is a schematic diagram of a cable distribution network includinga video on-demand source in accordance with a preferred embodiment ofthe present invention. In addition to the components of the conventionalcable distribution network shown in FIG. 1, the cable distributionnetwork shown in FIG. 4 includes a video on-demand source 402 and aremote server 404. The video on-demand source 402 may house, forexample, a collection of video programs such as, for example, movies. Asshown in FIG. 4, the remote server 404 may be located within thedistribution center 106. The remote server 404 may include, for example,a parallel processing computer configured to be a video server, a diskdrive array to store video data, and a video session manager to providesession control of the video data flowing to and from the video server.

FIG. 5A is a flow chart depicting a secure process for distributingvideo on-demand content via a cable distribution network in accordancewith a first aspect of the present invention. The process depicted inFIG. 5A may be called a store, decrypt, and re-encrypt process.

First, a video program is encrypted 502 by a video on-demand source 402to generate an encrypted program in a first encrypted form. Theencrypted program is transported 504 via a primary distribution networkfrom the video on-demand source 402 to a remote server 404 within adistribution center 106. The encrypted program is then stored 506 in theremote server 404.

Subsequently, when the remote server 404 receives 508 a request fortransmission of the video program from a subscriber station 110, theremote server 404 responds by first decrypting 510 the video programfrom the first encrypted form. A first key is may be used to accomplishsuch decryption 510, and such key may have been received from the videoon-demand source 402 via a communication channel that is separate fromthe one used to transmit the video program. After the video program isdecrypted 510, the remote server 404 re-encrypts 512 the video programinto a second encrypted form using a second key.

The second key may be a public key of a public key encryption system.Such a public key encryption system uses two different key: a public keyto encrypt data and a private key to decrypt data. In that case,decryption would be accomplished using a corresponding private key ofthe public key encryption system. Examples of such a public keyencryption system is encryption under the PGP (Pretty Good Privacy)system or under the RSA (Rivest, Shamir, and Adleman) system.Alternatively, the second key may be a private key of a private keyencryption system. Such a private key encryption system uses a singleprivate key to encrypt and decrypt data. Examples of such a private keyencryption system is encryption under the Data Encryption Standard (DES)or under triple-DES which involves applying DES three times to enhancesecurity. The private key(s) itself may be transmitted from the remoteserver 404 to the subscriber station 110 while encrypted in a thirdencrypted form.

After the video program is re-encrypted 512, the re-encrypted program inthe second encrypted form (and the second key if necessary) ismultiplexed 514 with other signals to generate a multiplexed signal. Themultiplexed signal is then distributed 516 via the secondarydistribution network 108 to the subscriber stations 110.

At the subscriber stations 110, the multiplexed signal is demultiplexed518 to isolate the re-encrypted program in the second encrypted form(and the second key if necessary), the re-encrypted program is decrypted520 from the second encrypted form to generate the unencrypted videoprogram, and then the video program is displayed 522, typically, on atelevision monitor connected to set-top box.

FIG. 5B is a flow chart depicting a secure process for distributingvideo on-demand content via a cable distribution network in accordancewith a second aspect of the present invention. The process depicted inFIG. 5B may be called a decrypt, re-encrypt, and store process. Incomparison with the process in FIG. 5A, the process in FIG. 5B decrypts510 and re-encrypts 512 the video program before the video program isstored 506 in the remote server 404.

First, a video program is encrypted 502 by a video on-demand source 402to generate an encrypted program in a first encrypted form. Theencrypted program is transported 504 via a primary distribution networkfrom the video on-demand source 402 to a remote server 404 within adistribution center 106. At this point, the remote server 510 decrypts510 the video program from the first encrypted form. A first key may beused to accomplish such decryption 510, and such key may have beenreceived from the video on-demand source 402 via a communication channelthat is separate from the one used to transmit the video program. Afterthe video program is decrypted 510, the remote server 404 re-encrypts512 the video program into a second encrypted form using a second key.After the decryption 510 and re-encryption 510, the re-encrypted programis then stored 506 in the remote server 404.

Note that step 506 in FIG. 5B differs from step 506 in FIG. 5A, in thatstep 506 in FIG. 5B involves storing the video program in the secondencrypted form, while step 506 in FIG. 5A involves storing the videoprogram in the first encrypted form.

Subsequently, when the remote server 404 receives 508 a request fortransmission of the video program from a subscriber station 110, theremote server 404 responds by multiplexing 514 the re-encrypted programin the second encrypted form (and the second key if necessary) withother signals to generate a multiplexed signal. The multiplexed signalis then distributed 516 via the secondary distribution network 108 tothe requesting subscriber station 110.

At the subscriber stations 110, the multiplexed signal is demultiplexed518 to isolate the re-encrypted program in the second encrypted form(and the second key if necessary), the re-encrypted program is decrypted520 from the second encrypted form to generate the unencrypted videoprogram, and then the video program is displayed 522, typically, on atelevision monitor connected to set-top box.

FIG. 6 is a flow chart depicting a secure process for distributing videoon-demand content via a cable distribution network in accordance with athird aspect of the present invention. The process depicted in FIG. 6may be called a pass-through process.

First, a video program is encrypted 602 by a video on-demand source 402to generate an encrypted program in a first encrypted form. Theencrypted program is transported 604 via a primary distribution networkfrom the video on-demand source 402 to a remote server 404 within adistribution center 106. A key to decrypt the encrypted program may alsobe transported from the source 402 to the server 404. The encryptedprogram is then stored 606 in the remote server 404.

The key may be a public key of a public key encryption system. Such apublic key encryption system uses two different key: a public key toencrypt data and a private key to decrypt data. In that case, decryptionwould be accomplished using a corresponding private key of the publickey encryption system. Examples of such a public key encryption systemis encryption under the PGP (Pretty Good Privacy) system or under theRSA (Rivest, Shamir, and Adleman) system. Alternatively, the key may bea private key of a private key encryption system. Such a private keyencryption system uses a single private key to encrypt and decrypt data.Examples of such a private key encryption system is encryption under theData Encryption Standard (DES) or under triple-DES which involvesapplying DES three times to enhance security. The private key(s) itselfmay be transmitted from the source 402 to the server 404 while encryptedin a second encrypted form. Alternatively, the private key(s) may betransported from the source 402 to the server 404 via a communicationchannel which is separate from the communication channel used totransport the video program from the source 402 to the server 404.

Subsequently, when the remote server 404 receives 608 a request fortransmission of the video program from a subscriber station 110, theremote server 404 responds by multiplexing 610 the encrypted program inthe first encrypted form (and the key if necessary) with other signalsto generate a multiplexed signal. The multiplexed signal is thendistributed 612 via the secondary distribution network 108 to therequesting subscriber station 110.

At the subscriber stations 110, the multiplexed signal is demultiplexed614 to isolate the encrypted program in the first encrypted form (andthe key if necessary), the encrypted program is decrypted 616 from thefirst encrypted form to generate the unencrypted video program, and thenthe video program is displayed 618, typically, on a television monitorconnected to set-top box.

FIG. 7 is a flow chart depicting a secure process for distributing videoon-demand content via a cable distribution network in accordance with afourth aspect of the present invention. The process depicted in FIG. 7may be called a multiple-layer encryption process. In comparison withthe process in FIG. 6, the process in FIG. 7 pre-encrypts 702 the videoprogram at the source 402, completes encryption 704 of the video programat the remote server 404, and fully decrypts 706 the video program atthe subscriber station 110.

The pre-encryption step 702 may be implemented by applying a single DESencryption or a double DES encryption. If the pre-encryption step 702uses a single DES encryption, then the completion of encryption step 704may be implemented by applying a double DES encryption to achievetriple-DES encryption. Similarly, if the pre-encryption step 702 uses adouble DES encryption, then the completion of encryption step 704 may beimplemented by applying a single DES encryption to achieve triple-DESencryption. In either case, the video program is transported from theremote server 404 to the subscriber station 110 while under triple-DESencryption. As long as the subscriber station has the three keysrequired, it will be able to fully decrypt 706 the triple-DES encryptionto obtain the unencrypted video program.

It is to be understood that the specific mechanisms and techniques whichhave been described are merely illustrative of one application of theprinciples of the invention. For example, while the present invention isdescribed in application to video on-demand, it also has someapplication in broadcast video. Numerous additional modifications may bemade to the methods and apparatus described without departing from thetrue spirit of the invention.

What is claimed is:
 1. A secure method performed by a remote server forproviding video programming requested by at least a first of a pluralityof subscriber stations, the method comprising: receiving the videoprogramming in a first encrypted form from a programming source; storingthe video programming in the first encrypted form; receiving a requestfrom a subscriber station for transmission of the video programming;decrypting the video programming from the first encrypted form;re-encrypting the video programming into a second encrypted form; andcausing transmission of the video programming in the second encryptedform to the subscriber station.
 2. The method as set forth in claim 1,wherein the video programming in the second encrypted form is to bedecrypted from the second encrypted form using a key.
 3. The method asset forth in claim 2, wherein the second encrypted form comprises a formof public-key encryption, and the key comprises a private key to decryptthe public-key encryption.
 4. The method as set forth in claim 2,wherein the key is transmitted to the subscriber station in a thirdencrypted form such that the subscriber station must decrypt the keybefore decrypting the video programming.
 5. The method as set forth inclaim 2, wherein the second encrypted form includes encryption utilizinga Data Encryption Standard.
 6. The method as set forth in claim 1,wherein a key is used to decrypt the video programming from the firstencrypted form, and wherein the video programming in the first encryptedform and the key are received from the programming source via separatecommunication channels.
 7. The method as set forth in claim 1, whereincausing transmission of the video programming in the second encryptedform to the subscriber station includes multiplexing the videoprogramming in the second encrypted form with other signals to create amultiplexed signal and causing transmission of the multiplexed signal tothe subscriber station.
 8. The method as set forth in claim 1, whereinthe remote server comprises a remote video on-demand server.
 9. Themethod as set forth in claim 1, wherein the remote server is locatedwithin a head-end, and the transmission to the subscriber station occursvia a secondary distribution network.
 10. The method as set forth inclaim 1, wherein the receiving from the programming source occurs via aprimary distribution network.
 11. A secure method performed by a remoteserver for providing video programming requested by at least a first ofa plurality of subscriber stations, the method comprising: receiving thevideo programming in a first encrypted form from a programming source;decrypting the video programming from the first encrypted form;re-encrypting the video programming in a second encrypted form; storingthe video programming in the second encrypted form; receiving a requestfrom a subscriber station for transmission of the video programming; andcausing transmission of the video programming into the second encryptedform to the subscriber station.
 12. The method as set forth in claim 11,wherein the video programming in the second encrypted form is to bedecrypted from the second encrypted form using a key.
 13. The method asset forth in claim 12, wherein the second encrypted form comprises aform of public-key encryption, and the key comprises a private key todecrypt the public-key encryption.
 14. The method as set forth in claim12, wherein the key is transmitted to the subscriber station in a thirdencrypted form such that the subscriber station must decrypt the keybefore decrypting the video programming.
 15. The method as set forth inclaim 12, wherein the second encrypted form includes encryptionutilizing a Data Encryption Standard.
 16. The method as set forth inclaim 11, wherein a key is used to decrypt the video programming fromthe first encrypted form, and wherein the video programming in the firstencrypted form and the key are received from the programming source viaseparate communication channels.
 17. The method as set forth in claim11, wherein causing transmission of the video programming in the secondencrypted form to the subscriber station includes multiplexing the videoprogramming in the second encrypted form with other signals to create amultiplexed signal and causing transmission of the multiplexed signal tothe subscriber station.
 18. The method as set forth in claim 11, whereinthe remote server comprises a remote video on-demand server.
 19. Themethod as set forth in claim 11, wherein the remote server is locatedwithin a head-end, and the transmission to the subscriber station occursvia a secondary distribution network.
 20. The method as set forth inclaim 11, wherein the receiving from the programming source occurs via aprimary distribution network.
 21. A secure method performed by a remoteserver for providing video programming requested by at least a first ofa plurality of subscriber stations, the method comprising: receiving thevideo programming in a first encrypted form from a programming source;storing the video programming in the first encrypted form; receiving arequest from a subscriber station for transmission of the videoprogramming; and responding to the request by causing transmission ofthe video programming in the first encrypted form to the subscriberstation.
 22. The method as set forth in claim 21, wherein the videoprogramming in the first encrypted form is to be decrypted from thefirst encrypted form using a key.
 23. The method as set forth in claim22, wherein the first encrypted form comprises a form of public-keyencryption, and the key comprises a private key to decrypt thepublic-key encryption.
 24. The method as set forth in claim 22, whereinthe key is transmitted to the subscriber station in a second encryptedform such that the subscriber station must decrypt the key beforedecrypting the video programming.
 25. The method as set forth in claim22, wherein the first encrypted form includes encryption utilizing aData Encryption Standard.
 26. The method as set forth in claim 21,wherein a key is used to decrypt the video programming from the firstencrypted form, and wherein the video programming in the first encryptedform and the key are received from the programming source via separatecommunication channels.
 27. The method as set forth in claim 21, whereincausing transmission of the video programming in the first encryptedform to the subscriber station includes multiplexing the videoprogramming in the first encrypted form with other signals to create amultiplexed signal and causing transmission of the multiplexed signal tothe subscriber station.
 28. The method as set forth in claim 21, whereinthe remote server comprises a remote video on-demand server.
 29. Themethod as set forth in claim 21, wherein the remote server is locatedwithin a head-end, and the transmission from the remote server to thesubscriber station occurs via a secondary distribution network.
 30. Themethod as set forth in claim 21, wherein the receiving from theprogramming source occurs via a primary distribution network.
 31. Asecure method performed by a remote server for providing videoprogramming requested by at least a first of a plurality of subscriberstations, the method comprising: receiving the video programming in apre-encrypted form from a programming source; storing the videoprogramming in the pre-encrypted form; receiving a request from asubscriber station for transmission of the video programming; completingencryption of the video programming to a fully encrypted form; andcausing transmission of the video programming in the fully encryptedform to the subscriber station.
 32. The method as set forth in claim 31,wherein the fully encrypted form comprises a triple-DES encrypted form.33. The method as set forth in claim 32, wherein the pre-encrypted formcomprises a single-DES encrypted form.
 34. The method as set forth inclaim 32, wherein the pre-encrypted form comprises a double-DESencrypted form.